The invention is directed to blue luminescent glasses, especially blue luminescent glass frits for glazing ceramic products.
Luminophores or fluoroscent substances are materials which are capable after absorbing energy (daylight, ultraviolet rays, x-rays, etc.) of emitting light. This light emission takes place with longer wave lengths than the absorbed radiation has and occurs during the excitation itself and in differing time intervals subsequently.
According to prevailing opinion the fluorescent substances are solid, crystalline compounds in which several cations of the base material are replaced by foreign cations, whereby the built in cations with the surrounding group of anions are conceived as so-called luminous centers. By comminuting the luminescent substance crystallite the ability to luminesce of the known luminophores is completely destroyed.
Amorphous materials with luminescent substance properties theoretically do not exist. Glass-like luminescent materials therefore previously have not been known.
For the product, for example of tiles having luminescent glaze coatings until now there have been fired mixtures of crystalline luminescent materials and customary glass frits. Thereby there cannot be exceeded temperatures of 700.degree.to 800.degree. C. since at higher temperatures which are necessary for firing on interesting glass frits, the luminescing materials are destroyed and no longer exhibit luminescent material properties.
Therefore it was the problem of the present invention to develop blue luminescing glasses, especially blue luminescing glass frits for glazing ceramic products.